Direct positive color photographic materials

ABSTRACT

A direct positive color photographic material having a silver halide photographic emulsion layer containing chemically fogged silver halide grains, said silver halide emulsion layer containing a magenta color coupler precursor having a pyrazole nucleus substituted by an acyloxy group at the five-position. The direct positive color photographic material containing such a magenta color coupler precursor has a high sensitivity, shows good clearness in the highlight portions, and has improved stability.

United States Patent [191 Shiba et al. Feb. 5, 1974 [5 DIRECT POSITIVECOLOR 2,706,685 4/1955 Salminen 96/100 PHOTOGRAPH: MATERIALS I 3,501,3073/1970 lllingsworth 3,501,312 3/1970 Mac at al 96/107 [75] Inventors:Keisuke Shiba; Kazuya Sano; Akio Okumura; Seiiti Kubodera, all ofKanagawa, Japan Primary ExaminerJ. Travis Brown [73] Assignee: FujiPhoto Film Co., Ltd., $23 ,2 1 Flrm sughme Rothweu Mlon Kanagawa, Japan[22] Filed: Sept. 13, 1972 [21] Appl. No.: 288,826 [57] ABSTRACT Adirect positive color photographic material having a [30] ForelgnApphcatlon Pnomy Data silver halide photographic emulsion layercontaining Se t. 13, 1971 Japan 46-71065 chemically fogged silver halidegrains, said Silver ide emulsion layer containing a magenta colorcoupler [52] US. Cl 96/100, 96/56.5, 96/60 R, precursor having apyrazole nucleus substituted by an 96/61 96/94 R, 96/107 96/108 acyloxygroup at the five-position. Thedirect positive [51] Int. Cl G03c l/40 1photographic material containing Such a [58] Field of Search 96/100,107, 108 gema color coupler precursor has a high sensitivity, shows goodcleamess in the highlight portions, and has 56] References Citedimproved stability.

UNITED STATES PATENTS 2,436,130 2/1948 Weissberger et al. 96/100 10Claims, 7 Drawing Figures PAIENTEBFEB 51914 Y 3199,39

FIG]

" mgsb 10 E RELATIVE VALUE 400 500 e00 700 WAVELENGTH m ,(nm)

400 500 600 70o WAVELENGTH 400 500 600 'YOOWAVELENGTH- v (nm) 400 500600 YOOWAVELENGTH v (nm) 400 500 600 700 WAVELENGTH DIRECT POSITIVECOLOR PHOTOGRAPIIIC MATERIALS BACKGROUND OF THE INVENTION visible raysand by a subsequent one step of a series of materials is generallyaccompanied with specific difficulties in comparison with the productionof negative photographic materials. In particular, the production of.

direct positive color photographic materials encounters moredifficulties. A first difficulty is that a sufficiently high sensitivityis hard to obtain. A second difficulty is that sufficient clearness ofthe highlight portions is hard to obtain. A third difficulty is that theflowable silver halide photographic emulsion to be used is poor instability and thus it is difficult to obtain consistent photo-.

graphic properties. A fourth difficulty is that color negative imagesappear in the highlight areas and thus the latitude tends to be narrow.

An object of this invention is to provide a direct positive colorphotographic material unaccompanied by the aforesaid difficulties.

SUMMARY OF THE INVENTION It has now been discovered that theabove-described difficulties are overcome by this invention. That is tosay, the above objects have been attained by using, as the photographicemulsion for the direct positive color photographic material, achemically fogged direct positive silver halide photographic emulsioncontaining a color coupler precursor having a-pyrazole nucleussubstituted by an acyloxy group at the five-position in the structuralformula. The acyl moiety of the acyloxy group indicated above includes,in addition to an aliphatic or aromatic group attached to a carbonylgroup (i.e., where the acyl group is aliphatic- II I C or aromatic l3but also an aliphatic or'aromatic group attached to the carbonyl groupthrough an oxygen atom (i.e., where the acyl group is aliphatic A firstfeature of the present invention is in the silver halide photographicemulsion used. That is to .say, the surface of the silver halide grainsof the photographic emulsion has been chemically fogged.

A second feature of this invention is in the use of a magenta colorcoupler precursor having a pyrazole nucleus substituted by an acyloxygroup at th e -p osition thereof is used.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS FIG. 1 is a graphicalrepresentation showing the photographic properties used in determiningthe characteristics of a silver halide emulsion used in this invention.

FIGS. 2-7 are spectrograms obtained for embodiments of the photographicmaterial of this invention.

DETAILED DESCRIPTION OF THE INVENTION Silver halide direct positivephotographic emulsions containing color couplers are known. For example,the direct positive silver halide photographic emulsions as describedabove are disclosed in the specifications of French Pat. Nos. 1,498,213;1,520,823; 1,522,354; and 1,520,819; British Pat. Nos. 1,186,711; and1,186,712; US. Pat. Nos. 3,501,307 and 3,501,312; and German Pat.Offenlegungsschrift No. 1,815.967.

Color couplers are those organic compounds which can form colored dyesin an aqueous solution containing a phenylenediamine derivative as thecolor developing agent and which is alkaline, preferably a pH of atleast 9.8 in the presence of silver halide grains which have becomedevelopable by being fogged by exposure or by a chemical treatment.Color couplers can be said to have,'in principle, a certain reducingpowerwith respect to the oxidation product of the color developingagent. As compounds useful as such color couplers, benzoylacetanilidederivatives, pivaloyl acetanilide derivatives, cyanoacetanilidederivatives, S-pyrazolone derivatives, indazolone derivatives,oxynaphthoic acid derivatives, and phenol derivatives are known.

The inventors have discovered that of these known color couplers the5-'pyrazolone derivative, when it is incorporated in a direct positivesilver halide photographic emulsion, greatly reduces the sensitivity ofthe emulsion, the clearness of the highlight portion, and also thestability of the emulsion. However, the 5- pyrazolone derivative, incontradistinction, is a coupler which has various excellent properties.That is to say, a S-pyrazolone derivative has an excellent couplingactivity, gives a color image having excellent spectral absorptions, andalso is easily available industrially.

However, the S-pyrazolone derivative, when it is used in direct positivesilver halide emulsions, gives rise to disadvantages are improvedremarkably by using a magenta color coupler precursor containing apyrazole nucleus substituted with an acyloxy group at the 5- I positionthereof.

Some of these effects have also been observed in regard to thebenzoylacetanilide couplers, etc, although the 5-acyloxy groupsubstituted pyrazole nucleus magenta color coupler precursor of thisinvention.

The silver halide photographic emulsions in this invention are generallyclassified into an A-type emulsion and a B-type emulsion.

That is to say, the A-type emulsion is a silver halide photographicemulsion which has been chemically fogged and has free electron trapnuclei in the silver halide grains:

A silver halide emulsion of this type gives a reversal image bysufficient exposure. Also, various attempts have been made to increasefurther the reversivity, i.e., the reversal sensitivity 'of silverhalide emulsions, to improve additionally the clearness of the highlightportions, and to prevent further the formation of negative images at thehighlight areas.

Firstly, some attempts have been made to form positively electron trapnuclei in the silver halidegrains for preventing the free electrons frombeing recomthe extent of the effects may differ from that by use ofbined with the positive holes. This method has been known for a longtime as a means of increasing the internal sensitivity of silver halidegrains. That is to say, there are a method wherein iodide ions areincorporated in silver halide emulsions that have not been chemicallyripened; a method wherein silver halide grains having sensitive nucleiobtained by chemical ripening are converted into inside nuclei byconverting the outer surfaces of the silver halide grains with anothersilver halide; and further a method wherein a salt of a metal belongingto Group VIII or Group lb of the periodic table is incorporated in thesilver halide emulsions in the step of precipitating the silverhalideare known (see, US. Pat. Nos. 2,401,051; 2,717,833; 2,976,149; and3,023,103; British Pat. Nos. 707,704; 1,097,999; and 690,997; FrenchPat. Nos. 1,520,822; 1,520,824; 1,520,817; and 1,523,626; Japanese Pat.Publication Nos. 4125/1968 and 29,405/1968; and Belgian Pat. Nos.713,272; 721,567; and 681,768).

Secondly, electron acceptors and/or halogen acceptors are adsorbed onthe surface of silver halide grains, whereby, in many cases, the silverhalide grains are spectrally sensitized toincrease the sensitivityandalso the clearness of the highlight portions is improved. The halogenacceptors used in this invention may be defined as M-band typesensitizing dyes. The electron acceptors used in this invention alsoincludes the socalled sensitizers and may be defined as materials havingthe ability to capture free electrons generated in silver halide grains.Those definitions are well known to one skilled in the art.

Thirdly, silver halide grains having the properties that the silverhalide grains have less positive hole-capturing sites in the grains andthe positive holes have suitable sizes for attacking the fogged nucleidisposed on'the surface of the silver halide grains. Bromide ions oriodide ions may also be used together with the halogen acceptor or theelectron acceptor.

On the other hand, the B-type emulsion is a silver halide photographicemulsion that has substantially no free electron trap nuclei in thesilver halide grains and which has been chemically fogged:

The original silver halide emulsion of this type can give less or noreversal images by itself and a direct positive image can be obtainedusing such a silver halide photographic emulsion by adsorbing theelectron acceptor on the surface of the silver halide grains. A silverhalide emulsion of this type has the following advantages. Firstly,because there are substantially no free electron trap nuclei in thesilver halide grains, negative images rarely appear at the highlightarea and thus a broad latitude is obtained. The free electron-trappednuclei of the silver halide grains tend to become developing centers. Inparticular, a color developing solution containing phenylenediamine asthe color developing agent has an essential property of developingreadily the developing centers in the silver halide grains. Secondly,the silver halide grains have no sites or a substantially smaller memberof sites for capturing free positive holes in the silver halide .grains.Electron trap nuclei in silver halide grains tend to become,disadvantageously, centers for recombination with positive holes.Thirdly, the use of the electron acceptor is inevitable. The propertiesof the electron acceptor exhibit an important role in the photographicproperties (see, Japanes efat. application No. 24,967/1971).

The A-type emulsion can be clearly and readily distinguished from theB-type emulsion by any of the following manners:

First, as original silver halide emulsions, the A-type emulsion can be adirect positive emulsion by itself, while the B-type emulsion cannotgive rise to sufficient positive images by itself.

Secondly, as finished silver halide emulsions, they can be distinguishedeach other by the following manner.

That is to say, the finished silver halide emulsion is applied to asupport such as a polyethylene terephthal-' ate film, a celluloseacetate film, or a glass sheet in a thickness below about 5 microns. Inthis case, the

amount of the coated silver is preferably so selected that the maximumoptical density obtained by development is 0.1 to 1.5. The coated sampleis cut into a strip and the strip is exposed behind an optical wedge toblue light obtained by passing the light from a tungsten lamp (2,854 K)through a Wratten Filter No. 478 or a K-3l Filter made by the Fuji PhotoFilm Co., Ltd.. Also,

. white light may be used in the exposure. In this case,

one of the samplesis exposed at normal temperatures and normalpressures, while the other sample is evacuated at room temperature formore than 17 hours under a high vacuum of below 10" mm. Hg and thenexposed under the high vacuum. Thereafter, each of the samples isdeveloped for 2 minutes at 20 C and then fixed. As the developingsolution, a D-72 developing solution, a D19 developing solution, or aPapitol developing solution having the following composition is used.

Compositionof D 72 Developing Solution N-Methyl-p-Aminophenol. SulfateSodium Sulfite (Anhydrous) Hydroquinone Sodium Carbonate (Anhydrous)Potassium Bromide Water to make Composition of D-l9 Developing SolutionComposition of Papitol Developer Solution Water to make At use, thecomposition is diluted with water in a 1 l by volume ratio.

By measuring the density of the strips thus obtained, the characteristiccurves are obtained. The characteristic curve (a) of the strip which wasexposed under normal temperatures and normal pressures and thecharacteristic curve (b) of the strip which was exposed at normaltemperatures under vacuum are shown in Table 1 and in FIG. 1 of theaccompanying drawings.

When the results of the measurement satisfy the following two factors,that the silver halide photographic emulsion used for the sample striphas substantially no free electron trap nuclei in the silver halidegrains is defined. That is to say, (1) where the minimum optical density(clearness of the highlight portions) of the latter strip describedabove, D,,,,,,(b), is 30 percent or more of the maximum density (foggeddensity at the unexposed area) of the former strip, D,, (a); i.e.,Dmi1l(b) Q.3 D ga) and (2) the sensitivity Sb at the point of /2 of themaximum density of the latter strip described above is reduced to 65percent or less of that Sa of the former strip; i.e., Sb 0.65 X Sa.

This definition can be applied additionally to direct positivephotographic materials as well as direct positive color photographicmaterials (in this case the photographic materials are developed using adeveloper formulation specific to the photographic material). Theaforesaid method discovered by the inventors is quite clear, precise,and reasonable method based mainly on the efficiency of the freeelectrons generated in silver halide grains being captured by theelectron acceptor adsorbed on the surface of the grains (see, JapanesePat. Publication No. 24,967/1971).

In the present invention any types of the emulsions as indicated abovemay be used but the use of the B-type emulsion is particularlypreferable. An example of preparing the B-type emulsion will beillustrated below.

PREPARATION EXAMPLE 1 To a first liquid prepared by dissolving 8g ofinert gelatin and 5 cc of a 1N aqueous solu tion gfpotas sium bromide in500 cc of water'by h eating the mixture to 60 C were added, a secondliquid prepared by dissolving 100g of silver nitrate in 500 cc of waterby heating the mixture to 60 C and a third liquid prepared by dissolving70g of potassium bromide in 1,500 cc of water by heating the mixture to60 C and then the mixture was subjected to physical ripening for 5minutes. Then, cc ofa 0.2 N solution of potassium iodide was added tothe emulsion thus ripened and after adjusting the pAg thereof to 6.0using an aqueous silver nitrate solution, hydrazine sulfate andpotassium chloroaurate were added to the emulsion. Then, after furtheradjusting the pH of the mixture to 10 using an aqueous sodium hydroxidesolution, the mixture was ripened further. Then, the mixture wasneutralized with citric acid and washed with water. Furthermore, aftermelting the resultant mixture, a fourth liquid prepared by dissolving75g of inert gelatin in 300 cc of water was added to the mixture toprovide a silver halide original emulsion. The silver halide grains inthe emulsion were grains of a regular tetragonal system having a meangrain size of about 0.2 micron and a (1,0,0) plane.

A typical example of preparing the A-type. emulsions will be illustratedbelow.

PREPARATION EXAMPLE 2 To a first liquid prepared by dissolving 10g ofinert gelatin and 5 E 9 N aq ussq ytiqnp sqdi n chloride in 500 cc ofwaterat 60 C were added with stirring simultaneously a second liquidprepared by dissolving g of silver nitrate in 500 cc of water at 60 Cand a third liquid prepared by dissolving 23g of sodium chloride and 23gof potassium bromide in cc of water, adding further 50 mg of potassiumhexachloroiridate (IV) (K IrCl to the solution, and maintaining themixture at 60C over a period of 20 minutes. Thereafter, 15 cc of a 0.2 Naqueous solution of potassium iodide was added to the mixture, theresultant mixture was set by reducing the temperature thereof, andwashed with water. Then, after meltingthe mixture, the pAg thereof wasadjusted to 4.0 and hydrazine sulfate and potassium chloroaurate (III)were added to the mixture. After adjusting, then, the pH of the mixtureto 10, the mixture was ripened for 10minutesand then neutralized to a pHof 6.5 using citric acid. Thereafter, the mixture was set by reducingthe temperature thereof and washed with water. After melting themixture, a mixture of a sodium chloride solution and a potassium bromidesolution was added to the mixture and then the pAg thereof was adjustedto 7.0. Thereafter, a fourth liquid prepared by dissolving 75g of inertgelatin in 300 cc of water was added to the mixture to provide a silverhalide original emulsion. The silver halide grains in the emulsionprepared above were the grains of a regular tetragonal system having amean grain size of about 0.15 micron and substantially, all of thegrains exhibited the (1,0,0).

The electron acceptors which can be used in this invention are disclosedin, e.g., the specifications of U.S. Pat. Nos. 3,023,102; 3,314,796;2,901,351; and 3,367,779; British Pat. Nos. 723,019; 698,575; 698,576;834,839; 667,206; 748,681; 796,873; 975,887; 905,237; 907,367; 940,152;and 1,075,654; French Pat. Nos. 1,520,824; 1,518,094; 1,518,095;1,520,819; 1,520,823; 1,520,821; and 1,523,626; Belgian Pat. Nos.722,457 and 722,594; and Japanese Pat. Publication Nos. 13167/1968 and14500/1968.

Also, the halogen acceptors which can be used in this invention aredisclosed in, e.g., the specifications of U.S. Pat. Nos. 2,497,876 and3,364,026; French Pat. Nos. 1,520,822 and 2,012,545; British Pat. No.655,009; and German Pat. No. 1,190,331. The electron acceptor and thehalogen acceptor used in this invention are preferably ones having atleast one sulfo group, carboxyl group, or phosphate group.

The direct positive silver halide photographic emulsion in thisinvention may be chemically fogged in the following way. That is to say,fogged nuclei are obtained by adding to the silver halide emulsion aninorganic reducing compound such as stannous chloride, sodiumborohydride, and cuprous chloride or by adding an organic reducingcompound such as hydrazine, a hydrazine derivative, formalin, thioureadioxide, a polyamino compound, an amine borane, andmethyldichlorosilane. Also, metal ions. having a lower ionizationpotential than silver ions or halide ions may be used together with theabove-indicated reducing agent for further improving the stability ofthe fogged nuclei and facilitating the breakage of the fogged nuclei bypositive holes (see, U.S. Pat. Nos. 2,497,875; 2,588,982; 3,023,102; and3,367,778; British Pat. Nos. 707,704; 723,019; 821,251; and 1,097,999;French Pat. Nos. 1,513,840; 1,518,095; 739,755; 1,498,213; 1,518,094;1,520,822; and 1,520,824; Belgian Pat. Nos. 708,563

I and 720,660; and Japanese Pat. Publication No.

A l-phenyl(substituted or unsubstituted)-3- amylamino-pyrazole couplersubstituted by an msulfobenzoxy group at the 5-position is disclosed inthe specification of U.S. Pat. No. 2,706,685.

However, the object of this U.S. Patent is to provide a coupler havingan alkali-soluble group so that it can be dispersed as an aqueoussolution thereof in a negative silver halide emulsion and further toprovide a coupler having a high coupling activity. Accordingly, such adisclosure in the patent differs fundamentally from the objects of thisinvention.

Many methods are known for dispersing color couplers in hydrophiliccolloids. According to one of those known methods, a coupler having inthe coupler molecule a water-soluble group such as a sulfo group, acarboxyl group, a hydroxyl group or an amino group is incorporated in asilver halide emulsion in a micellar state as an aqueous solution or analkali solution thereof. In another method, a coupler is solubilized ina surface active agent and then the coupler is incorporated in a silverhalide emulsion. According to still another method, at least a part ofan oil-soluble color coupler substantially insoluble in water (having asolubility in water of less than 1%) is dissolved in a high boilingplasticizer such as tricresyl phosphate, dibutyl phthalate, a biphenylether derivative, and oil (including fats) and then dispersed in asilver halide emulsion as fine particles using a surface active agent.By even another method, when an oil-soluble coupler itself is in an oilystate or in a liquid state at high temperatures, the coupler is directlydispersed, as liquid, in a silver halide emulsion using a surface activeagent. By another method a color coupler is dispersed physically in asilver halide emulsion as fine solid particles. According to an anothermethod a'color coupler is dispersed in a silver halide emulsion togetherwith a hydrophilic colloid utilizing the coaction between the couplermolecule and the colloid molecule. Any methods described above can beused in this invention but the third, fourth, and sixth methods asdescribed above are particularly useful. 1

The color coupler precursor used in this invention is a coupler having apyrazole nucleus substituted by an acyloxy group at the 5-positionthereof and it may be represented by, for example, the following generalformula:

wherein A represents a monocyclic aryl group, such as a phenyl group, achlorophenyl group, a methylphenyl group, an ethylphenyl group, anethoxyphenyl group, a

cyanophenyl group and a substituted derivative thereof wherein thefurther substituent may be a halogen atom such as chlorine and/or analkyl group such as a methyl group; W represents an alkyl group, such asa methyl group, an ethyl group, a propyl group, a butyl group, achloromethyl group, a methoxymethyl group, a methoxyethyl group, anethoxyethyl group, a phenoxymethyl group, a benzyl group, and asubstituted derivative thereof wherein the further substituent may be ahalogen atom such as chlorine and/or an alkyl group such as a methylgroup or an aryl group, such as a phenyl group, a chlorophenyl group, abromophenyl group, a methoxyphenyl group, a nitrophenyl group, a tolylgroup, a naphthyl group, a chloronaphthyl group, and a substitutedderivative thereof wherein the further substituent may be a halogen atomsuch as chlorine and/or an alkyl group such as a methyl group; and Zvrepresents a diffusion resisting balasting group, preferably anacylamino group, a ureido group, or the like which are well known to oneskilled in the art. The balasting group is preferably those havinggreater than 8 carbon atoms.

Now, the specific examples of the color coupler precursors used in thisinvention are given below although the color couplers are not limited tothese compounds only.

who;

C iisHaicoNH Each of those acyloxypyrazoles may be prepared bycondensing a triethylamine salt of the corresponding pyrazolone and anacid chloride. For example, Coupler (01) may be prepared by thefollowing manner.

SYNTHESIS EXAMPLE 1 60 g of l-(2,4,6-trichlorophenyl )-3-( 3-hexadecaneamidobenzamido)-5-pyrazolone and g of triethylamine were addedto 400 ml of acetonitrile and after dissolving the additives by heating,the solution prepared was cooled with ice, thereby colored 10 crystalswere precipitated. By recovering the crystals thus precipitated byfiltration and drying them, 65 g of the triethylamine salt of thepyrazolone was obtained.

The entire amount of the salt obtained above was dissolved in 350 ml ofacetonitrile and after adding thereto 13 g of acetyl chloride, theresultant mixture was refluxed for 2 hours. When the mixture was, then,cooled with ice, colorless crystals were precipitated. When the crystalswere recovered by filtration, washed with acetonitrile, andrecrystallized quicl ly from 230 are? massif, 29 g (FC oupler C-Dhavinga melting point of 1 15 C was obtained. I

Other acyloxy pyrazoles used in this invention may also be prepared in asimilar manner according to the method shown in the above SynthesisExample 1.

Comparison color couplersused in the comparison examples are as follows:

(7.5? ii'siil' o'oiiiii A For the silver'ha'lid'e emulsion in thisinvention, a gel atin protective colloid, in particular inert gelatin isadvantageously used. In place of such gelatin, a partially inert gelatinderivative and hydrophilic synthetic polymers such as polyvinylacrylate, polyvinyl alcohol, polyvinyl pyrrolidone, and polyvinylalgina'te may also be used. The silver halide grains used in thisinvention are grains of silver salts composed of chloride ions, bromideions, iodide ions, or a mixture of these ions. However, for the B-typeemulsion it is preferable to use silver bromide or silver iodobromide.The electron acceptor or the halogen acceptor is preferably used in anamount of l X 10 mol to 5 X 10" mol per mole of the silver salt orsalts.

The silver halide emulsion used in this invention may contain materialshaving known functions and used in conventional light sensitivematerials, for example, a

stabilizer for fogged nuclei, such as a mercapto compound, a thioncompound, a tetrazole derivative, and a tetrazaindene derivative; animproving agent for clearness, such as a stilbene compound and atriazine compound; a ultraviolet absorbing dye for improving COMPARISONEXPERIMENT A silver chlorobromide emulsion prepared in a conventionalmanner for the production of the A-type emulsion was placed in threepots each in an amount of 100 g and was heated to 40 C. Then, 20 cc of a5 wt% ethyl acetate solution 5f the compoundt'c 'nwas' added to thefirst pot while stirring vigorously with ultrasonic waves. Further, 20cc of a 5 wt% ethyl acetate solution of the comparison compound (A) wassimilarly added to the second pot. Also, 20 cc of a 5 wt% alkalineaqueous solution of the comparison compound (B) was added to the thirdpot and then the mixture in the third pot was neutralized (to the pH of6.5) using an aqueous citric acid solution.

To each of the emulsions thus prepared were added 4 cc of a 2% aqueoussolution of sodium dodecylbenzenesulfonate and 4 cc of a 2% aqueoussolution of 2,4- dichloro-6-hydroxy-S-triazine. Then, the emulsion wasimmediately applied to a cellulose triacetate film so that the drythickness was about 6 microns.

Each of the three kinds of samples was exposed through an optical wedgeto light of a tungsten lamp of 2,854 K and then processed usingfollowing steps:

(I) Color Development 29.5C 6 min. (2) Stop Fixing 2 min. (3) Rinse 2min. (4) Bleaching 2 min. (5) Rinse 2 min. (6) Hardening Fixing 4 min.(7) Rinse 4 min. (8) Stabilization 2 min. (9) Drying By measuring thedensities of the strips thus obtained through a green filter,characteristic curves were obtained, the results of which are shown inTable 1.

Table 1 Coupler Photographic Properties No. Type- W Relative MinimumEmulsion Compound Amount Sensitivity Density (100g) l A-type (C-l) l g I0.l4 2 (A) 28 0.32 (B) 0.65

' The relative sensitivity was less than 5 and thus an accuratemeasurement of the sensitivity was not obtained.

' The sensitivity at the density point of A of the maximum density.

From the results shown in Table I, it can be seen that .t sgqssnta saurltprsqa sm. sed n this inxc r Compound (01). gave rise to excellentproperties such as less fog and a remarkably high sensitivity incomparison with the known pyrazolone couplers (A) and (B).

The compositions of the processing baths used in the above processingswere as follows:

Color Developing Solution Sodium Mctahorate 25.0 g Sodium Sulfite 2.0 gHydroxylamine Sulfate 2.0 g Potassium Bromide 0.5 g o-NitrobenzimidazoleNitrate 0.02 g Sodium Hydroxide 4.0 g Benzyl Alcohol 15.8 cc DiethylencGlycol 20.0 cc N-Ethyl-N-B-(methancsulfoamidoJ-p-phcnylenediaminc 8.0 gWater added to make I liter (pH l().6)

Stop Fixing Solution Ammonium Thiosulfate v 120.0 g Sodium Metabisulflte20.0 g Glacial Acetic Acid 10.0 g Water added to make 1 liter (pH 4.5)

Bleaching Solution Potassium Nitrate 25.0 g Potassium Ferricyanide 20.0g Potassium Bromide 8.0 g Boric Acid 5.0 g Borax 2.5 g Water added tomake 1 liter (pH 7.2)

Hardening Fixing Solution Ammonium Thiosulfate l20.0 g Sodium Sulfite5.0 g Boric Acid 2.5 g Formalin (3540 percent) 40.0 cc Water added tomake 1 liter (pH 9.5)

EXAMPLE 1 A silver iodobromide emulsion prepared in a conventionalmanner for the preparation of the B-type emulsion was placed in each potin an amount of 1 Kg and melted at 40 C. Then, a electron acceptor or amixture of an electron acceptor and a halogen acceptor as shown in Table2 were added to the emulsion for adsorption on the silver halide grains.The emulsion was 7 then allowed to stand for about 20 minutes.Thereafter,

59912929. of smu sifissl. dispersion d qr d hereinafter, of thecompounds (O1), (C-2), (C-3), (C-4), and (C-5) of this invention shownin Table 2 was added to the emulsion followed by stirring.

Then, 10 cc of a 2% aqueous solution of Ntetradecyl-N,N-di-polyoxyethylene betaine and 10 cc of a 2% aqueoussolution of 2,4-dichloro-6-hydroxy-S- triazine were added to the silverhalide emulsion to provide a finished silver halide emulsion. Theemulsion was applied to a transparent cellulose triacetate film anddried so that the dry thickness of the emulsion layer was about 6microns.

The emulsified dispersion of the coupler precursor of this inv e n t iori t 1sed above was prepared by the following manner. That is to say. 1Kg of a 10 wt% aqueous solution of inert gelatin was heated to 60 C.Thereafter, cc of a 5% aqueous solution of sodium dodecylbenzenesulfonate was added to the emulsion. On the other hand, 0.15 mole of thecoupler precursor was added to a mixture of 100 g of dibutyl phthalateand 50 cc of butyl acetate and the former was dissolved completely inthe solvent mixture by heating. The solution thus prepared was added tothe gelatin solution prepared above, dispersed immediately in thegelatin solution using a high speed rotary mixer and a ultrasonicvibrator, and after adding further 1 Kg of water to the dispersionfollowed by stirring, the mixture was set by cellent photographicproperties such as a very high senrapid cooling. sitivity and lessformation of fog in comparison with The photosensitive films preparedabove were subconventional materials are obtained by using the ma jectedto sensitometry according to the procedure as genta coupler precursorhaving a pyrazolone nucleus shown in the Comparison Experiment 1. Theresults of substituted with an acyloxy group at the 5-position thewhichare shown in Table 2. reof.

TABLE?" Sensitizing Dye Photographic Properties spectrogram No. CouplerPrecursor Electron Acceptor Halogen Acceptor Relative Minimum Density(amount) Sensitivity -4 (C-l) (8-!) (0.4 millimole) None 100 0.12 FIG. 25 02 (S-l)(0.6 125 0.11 FIG. 3 6 (C-3) (s-2 0.4 400 0.12 FIG. 4 7 c4s-3)(0.3 400 0.11 FIG, 5 s (05 s-4 0.4 250 0.11 FIG. 6 9 05) (8-1 04s-5) 0.2 millimole) 175 0. 12 FIG. 7

2 The sensitivity at the sensity point of H2 of the maximum density. N W1 The chemical structural formulae of the sensitizing dyes used in thisexample were as follows:

(s-1): Thep hotosensitive film coated thereon with the direct positivesilver hallde photographic emulsion in accordance with the presentinvention can be prepared \N/ by the conventional procedure. Suitablesupport for the photosensitive film includescellulose esters such as Scellulose diacetate, cellulose triacetate, cellulose ace- A' N02 tatebutyrate and the like, synthetic resin films such as CH=CH lpolyethylene terephthalate, polystyrene, polycarbon- 3Q ate,polyethylene, polypropylene, polyvinyl'acetal films The thickness of theemulsion layer containing the magenta coupler precursor can range from 1to 20 u. The amount of the color coupler can range from 2 to l/lOO moleper one mole of silver halide, preferably from 1 to 1/60 mole. Suitableamount of silver halide can range from 5 mg to 200 mg, preferably from10 mg to 100 mg per 100 cm of the coating based on the 40 amount ofsilver.

While the invention has been described in detail and with reference tospecific embodiments thereof, it will be apparent to one skilled in theart that various changes and modifications can be made therein withoutdeparting from the spirit and scope thereof.

What is claimed is:

o N N 1. A color photographic material giving colored im- N02 ages bycolor developmentin a color developing solu- CH=CHCH= L tion containinga phenylenediamine as the color devel- ,t \N i and the like, glass,paper, a laminate of paper and a m a resin such as polyethylene, a metalplate and the like.

5 oping agent comprising a support having thereon at least one directpositive silver halide photographic H9430- emulsion layer, said silverhalide emulsion layer containing silver halide grains in which thesurface of said grains are chemically fogged and said silver halideemulsion layer containing a magenta color coupler precursor having apyrazole nucleus substituted with an O acyloxy group at the 5-positionof said pyrazole nucleus. Q CH CH CH 2. The color photographic materialas set forth in claim 1, wherein said silver halide emulsion has thefol- (flmofksor 4313920114, OaHN (ozHm lowing characteristics:

Ha Ha g X D -A3.)

and

From the above descriptions, in particular the results 0 shown in Tablel and Table 2, it can be seen that the Sb direct positive colorphotographic materials having exwherein D (b) is the minimum opticaldensity of the silver halide emulsion coated on a test strip, subjectedto a vacuum of below mmHg for more than 17 hours, exposed to a bluelight through an optical wedge under said vacuum and developed, whereinD, (a) is the maximum optical density of the silver halide emulsioncoated on a test strip, ex-

posed to a blue light through an optical wedge and wherein A representsa monocyclic aryl group, W rep resents an alkyl group or an aryl group,and Z represents a diffusion resisting acylamino group or a diffusionresisting ureido group.

4. The color photographic material as set forth in claim 1, wherein saidcolor coupler precursor is a compound represented by the formula whereinA represents a monocyclic aryl group, W represents an alkyl group or anaryl group, and Z represents a diffusion resisting acylarnino group or adiffusion resisting ureido group.

5. The color photographic material as set forth in claim 1, wherein saidsilver halide grains of said silver halide photographic emulsion haveadsorbed thereon an electron acceptor having at least one of a sulfogroup, a carboxyl group, or a phosphate group.

6. The color photographic material as set forth in claim 1, wherein thesilver halide grains of said silver halide photographic emulsion haveadsorbed thereon an electron acceptor having at least one of a sulfogroup, a carboxyl group, or a phosphate group and a halogen acceptorhaving at least one of a sulfo group or a carboxyl group.

7. The color photographic material as set forth in claim 1, wherein saidsilver halide grains are chemically fogged using stannous chloride,sodium borohydride, cuprous chloride, hydrazine, a hydrazine derivative,formalin, thiourea dioxide, a polyamino' compound, an amine borane, ormethyl dichlorosilane.

8. The color photographic material of claim l, wherein said emulsion isa gelatin emulsion and wherein saidsilver halide is silver chloride,silver bro-- mide, silver iodide, or mixtures thereof.

9. The color photographic material as set forth in claim 6, wherein saidelectron acceptor and said halogen acceptor are present at a level offrom 1 X l0 to 5 X 10 mole per mole of silver halide.

10. A color photographic element comprising a support having thereon atleast one layer of the color photographic material of claim 1.

2. The color photographic material as set forth in claim 1, wherein said silver halide emulsion has the following characteristics:
 1. Dmin (b) 0.3 X Dmax (a) and
 2. Sb < or = 0.65 X Sa wherein Dmin (b) is the minimum optical density of the silver halide emulsion coated on a test strip, subjected to a vacuum of below 10 4 mmHg for more than 17 hours, exposed to a blue light through an optical wedge under said vacuum and developed, wherein Dmax (a) is the maximum optical density of the silver halide emulsion coated on a test strip, exposed to a blue light through an optical wedge and at normal pressures and developed, wherein Sa is the sensitivity of the silver halide emulsion at said maximum optical density obtained at normal pressures, wherein Sb is the sensitivity of the silver halide emulsion at 1/2 of the maximum optical density of the silver halide emulsion evaluated at under said vacuum.
 3. The color photographic material as set forth in claim 1, wherein said color coupler precursor is a compound represented by the formula
 4. The color photographic material as set forth in claim 1, wherein said color coupler precursor is a compound represented by the formula
 5. The color photographic material as set forth in claim 1, wherein said silver halide grains of said silver halide photographic emulsion have adsorbed thereon an electron acceptor having at least one of a sulfo group, a carboxyl group, or a phosphate group.
 6. The color photographic material as set forth in claim 1, wherein the silver halide grains of said silver halide photographic emulsion have adsorbed thereon an electron acceptor having at least one of a sulfo group, a carboxyl group, or a phosphate group and a halogen acceptor having at least one of a sulfo group or a carboxyl group.
 7. The color photographic material as set forth in claim 1, wherein said silver halide grains are chemically fogged using stannous chloride, sodium borohydride, cuprous chloride, hydrazine, a hydrazine derivative, formalin, thiourea dioxide, a polyamino compound, an amine borane, or methyl dichlorosilane.
 8. The color photographic material of claim 1, wherein said emulsion is a gelatin emulsion and wherein said silver halide is silver chloride, silver bromide, silver iodide, or mixtures thereof.
 9. The color photographic material as set forth in claim 6, wherein said electron acceptor and said halogen acceptor are present at a level of from 1 X 10 6 to 5 X 10 3 mole per mole of silver halide.
 10. A color photographic element comprising a support having thereon at least one layer of the color photographic material of claim
 1. 